1. Field of the Invention
The present invention relates generally to a system and method for purging bubbles from a fluid ejection head and, more particularly to controlling the amount of ink ejected from the ejection head during a purging operation.
2. Description of the Related Art
Ink jet printers have a permanent fluid ejection head, which are not typically replaced by the customers. Rather, the supply item in this case that is replaced is the fluid cartridge mounted on the fluid ejection head. Air management in the fluid cartridge is an issue, since air can enter the fluid cartridge from several different sources resulting in blockage in the fluid ejection head that result in poor print quality if that air is not removed.
To purge bubbles, an air tight seal is provided around a plurality of fluid ejection nozzles of the fluid ejection head. The air tight seal has an opening at one end through which a negative pressure is exerted on the plurality of fluid ejection nozzles. The negative pressure removes ink and unwanted bubbles from the fluid ejection head. The fluidic resistance of the fluid ejection head determines the amount of ink removed during the purging operation. Some of the features that affect the fluidic resistance of ink are flow path length, area of the fluid ejection head, nozzle diameter, and fluid viscosity. Usually, there are significant differences in the flow features and fluid viscosity of monochrome ink compared to color ink.
Due to these differences, when the same pressure is applied to the monochrome ink and color ink during a purging operation, one of the color or monochrome ink is removed more than is needed.
Therefore, it would be advantageous to have a system that can control the amount of ink removed from the fluid ejection head during a purging operation.